Extracellular vesicles include exosomes or microvesicles, having a size of about 50 to 1000 nm, and are thus useful as markers for diagnosing disease because they retain the characteristics of original cells.
Conventional techniques for isolating extracellular vesicles include ultracentrifugation, antibody isolation, a microfluidic method, and polymeric precipitation. Among these, the ultracentrifugation method is widely employed in the isolation of extracellular vesicles and is regarded as the most reliable by virtue of the simple principle therefor.
However, the case where extracellular vesicles are isolated using ultracentrifugation is problematic in that the yield of extracellular vesicles is low, the isolation time thereof is long, and expensive devices are required therefor.
The antibody isolation method, which adopts an antigen-antibody reaction, has high selectivity but makes it difficult to remove the antibody attached to vesicles and is unsuitable for mass production owing to the high price of the antibody.
The microfluidic method enables the rapid isolation of vesicles from a small amount of a sample by combining the antibody isolation with the microfluidic chip, but the application of the antibody to the microfluidic chip requires many preparation procedures.
The polymeric precipitation method enables the simple isolation of vesicles, but is disadvantageous in that all materials present in the sample precipitate and thus impurities such as proteins may be included therewith.
With the goal of overcoming the problems with conventional techniques, the present inventors have disclosed Korean Patent Application Publication No. 2014-0050465 regarding a microfluidic chip for isolating extracellular vesicles. The above patent is economically advantageous because extracellular vesicles are isolated from serum using an antibody-coated microfluidic chip, thus enabling extracellular vesicles to be isolated quickly and obviating the need for a laboratory, but is disadvantageous in terms of low yield, and hence, there are still problems to be solved in order to realize suitability for use in practical and economical diagnosis methods.
Meanwhile, the polymeric method decreases the solubility of body fluids to thereby precipitate extracellular vesicles, but requires a long incubation time, and moreover, proteins are precipitated therewith, thus resulting in low precipitate purity, making this method unsuitable for use in diagnosis.